Sousa notched his first win over an ATP Top 10 player with a 6-2, 7-6 (8-6) decision over Ferrer. Sousa converted all three of his break chances and won three of the four break opportunities Ferrer had.
Sousa dropped only five points on serve in the first set and took 60 percent of the points when serving in the second set.
He'll be looking for his first ATP finals berth when he plays fourth-seeded Jurgen Melzer in Saturday's semifinals.
Melzer swept past Federico Delbonis 6-3, 6-2 Friday by winning 71 percent of the points on serve and nearly half -- 30-of-61 -- when receiving .
Wawrinka managed just one break but that enabled him to win the second set. Both players saved a break point in the third set before Wawrinka jumped out to an early lead in the tiebreaker and advanced.
Julien Benneteau, the No. 5 seed, got by Adrian Mannarino 6-3, 6-3 with five breaks in the other quarterfinal.
Sousa defeated Melzer in Acapulco earlier this year in their only previous meeting. Wawrinka and Benneteau have split their two earlier matches.